Hello Jan,
There isn't a short way to explain this, so please bear with me.
I figured out what Preview was doing in the above where the cyan patch was split, and everything to the right of that displaying incorrectly. The patches up to the band were the correct color, and the rest of the image was displaying as sRGB. On the sRGB version of the strip, Preview was correctly displaying sRGB values up to the same point, but the rest of it to the right - well - who knows what that was supposed to represent. So there's one bug to submit to Apple.
Second bug is ColorSync's Calculator. It's just kind of backwards how you use it. You pick the color with the magnifier you want a reading of first, then choose the color space you want from the menus. The color shown is still wrong, though. If I select the same pink, and then set the drop down menu to my monitor profile (which is the color space the strip of patch colors is in), they should perfectly match. You can see below they don't. The small rectangle inside the pink area is how the calculator is showing what is supposed to be exactly the same color. The Digital Color Meter even reads them as different RGB values. So bug number two to submit.
I see the color meter reports sometimes RGB with the notation "clipped" usually when the channel is 0 or 255, but not every time (see example below).
That's actually correct. It would be clipped in sRGB. The two main things to know about color as a computer understands it (and any device you can use with a computer that handles color, such as a digital camera, scanner, printer, etc.), are these:
1) The only color space in which each and every color is a fixed point, and will always be that color no matter how many times you express a given value, is L*a*b*. CIE L*a*b* is the current model we use. As a short explanation, it's every color we are capable of seeing defined as a mathematical model so computers have a consistent reference point. Not that the same L*a*b* color will look the same on every computer since they are all over the place as far as the color range a particular monitor can display, and how it's been profiled.
2) All RGB color spaces are a portion of L*a*b*. It tells the computer how much of L*a*b* a particular scanner, monitor, printer or whatever is capable of reproducing. Everybody makes a big deal out of Adobe RGB being some sort of standard. Well, I hate to be the one to break it to everyone else, but it's just one of millions of RGB color spaces. All of which are just as "independent" as Adobe RGB (2008) is claimed to be. If I took my monitor profile, which outdoes Adobe RGB's range in many hues, and called it Adobe RGB (2015), no one would known the difference. At least until Adobe made it known they didn't release such a color space. But it would be just as valid at being an independent color space as any other RGB profile.
So, what is clipping? Take a look at this comparison:
This is Adobe RGB and sRGB displayed together. Adobe RGB being the larger space. The points circled in red are both the most saturated green each space can display. Both of which will read 0,255,0 when working in that color space. The points circled in green are those two space's most saturated red (which don't look very red due to the angle of the 3-D view). Both of which will read as 255,0,0. The next picture will make this easier to visualize:
The patch on the left is the pure red on my EIZO monitor. The one on the right is the brightest red, also defined as 255,0,0, that sRGB can show. Obviously note even close to the same color, despite both being 255,0,0. The giveaway why they're different are the L*a*b* values for each one. They are at completely different L*a*b* coordinates, just like the green circled areas above.
That's what clipping means. sRGB is incapable of having the native hue exist within its space, so it lets you know that you are working with a color that is outside of sRGB's realm. And just for fun, let's convert the 255,0,0 sRGB color pictured just above to my monitor profile. Look what happens to the RGB values:
It's not 255,0,0 anymore. In order to keep that color in exactly its same point of reference to L*a*b*, it became 206,43,13 in my monitor's RGB profile space. If I were to do it the other way around (my monitor's 255,0,0 color to sRGB), then it would still be 255,0,0, but would become the duller red above since the conversion would force the more brilliant red down to the nearest point that can exist in sRGB.
Native to what?
Native in the Digital Color Meter meaning the RGB values are a reading of whatever your monitor profile is.
